The towing industry has developed a number of methods and apparatuses for securing a towed vehicle or trailer to a towing vehicle. For example, hitch balls have been developed to be attached to the bumper or other rear portion of a towing vehicle. A trailer or towed vehicle equipped with a coupler mechanism may be attached to the towing vehicle by placing the coupling mechanism over the hitch ball and securing the coupler to the ball. Similar apparatus using hitch receivers attached to the rear of a towing vehicle and drawbars may be used to secure trailers to towing vehicles.
Some trailers may be designed to carry heavy loads. Connecting such a trailer to a ball hitch on a bumper of a towing vehicle, however, may be impractical. When a trailer load is heavy when compared to the weight of the towing vehicle, applying the trailer load to the rear of the towing vehicle may cause undesirable towing conditions. In such situations, the trailer may often be secured to a load bed of a towing vehicle, whereby the force of the trailer load is generally applied over or near the rear axle of the towing vehicle to create a potentially more stable towing condition. In addition, such an arrangement may put much of the force of the trailer load onto structural members of the towing vehicle, such as the frame.
There are generally two arrangements for securing a trailer to the load bed of a towing vehicle—a fifth wheel hitch and a gooseneck hitch. A gooseneck hitch is generally attached to a hitch ball that may be located in the load bed of the towing vehicle. The hitch ball may typically be secured to the frame or load bed of the towing vehicle. A fifth wheel hitch may generally be positioned in a load bed of the towing vehicle and secured either to the load bed or directly to the frame of the towing vehicle. Fifth wheel hitches may generally be attached to the load bed or frame whereby tools may generally be required to remove fasteners and other connectors to install or uninstall a fifth wheel hitch to the load bed of a towing vehicle.
Typically, a fifth wheel trailer may include a king pin that may be used to couple the trailer to the towing vehicle. Fifth wheel trailers are commonly coupled to towing vehicles that include a load bed, such as a pick-up truck or a flatbed truck. A fifth wheel hitch assembly may be secured in the load bed of the towing vehicle, whereby the king pin of the trailer is commonly coupled to the fifth wheel hitch assembly.
Fifth wheel hitch assemblies may typically include a support frame for securing the hitch assembly to the load bed of the towing vehicle. The support frame may include a pair of mounting rails, a pair of side brackets, and a head assembly. The mounting rails may be bolted to the load bed or the frame of the towing vehicle. The side brackets may be secured to the mounting rails and the head assembly may be secured to the side brackets. The head assembly may be secured in a manner that allows the head assembly to pivot fore-and-aft with respect to the towing vehicle.
The head assembly may include a jaw assembly for securing the king pin of the trailer to the towing vehicle. The jaws may be moveable to secure and release the king pin extending from the trailer. The jaws may also be arranged such that an operator may manually toggle the jaws between a position in which the king pin is secured in the jaws and a position in which the king pin is released from the jaws. When the king pin is secured in the jaws, the trailer is secured to the towing vehicle and may be towed by the towing vehicle. When the king pin is released from the jaws, the king pin may be removed from the jaws, decoupling the trailer from the towing vehicle.
Fifth wheel hitches may normally be arranged such that the king pin is aligned over or near the rear axle and approximately equidistant between the rear wheels of the towing vehicle. Placing the king pin over the rear axle may also provide for sufficient clearance between the front edge of the trailer and the rear edge of the towing vehicle cabin. Such an arrangement may facilitate towing the trailer at operational speeds, such as highway speeds.
Driving a fifth wheel trailer may often be very rough, whereby large shocks can pass through the trailer hitch between the trailer and the towing vehicle. Providing a rigid trailer hitch, however, may not provide an adequate or proper cushion between the stiff trailer and the towing vehicle, whereby the people traveling in the towing vehicle may not have a comfortable ride.
Typically, fifth wheel hitches have either used large volume air bags, fluid shock absorbers, or have been forced to use a dense polymer to limit the resulting displacement. As a result, fifth wheel hitches have required a large amount of space and have not been able to adequately dampen high frequency vibrations as well as low frequency vibrations. In addition, fifth wheel hitches generally dampen a limited number of degrees and not multiple axes.